Tübingen 2003 – wissenschaftliches Programm
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HK: Physik der Hadronen und Kerne
HK 26: Theorie III
HK 26.1: Gruppenbericht
Mittwoch, 19. März 2003, 10:45–11:15, D
Quark flavor dependence of chiral symmetry restoration — •Jörg Ruppert, Christian Beckmann, Stefan Strüber, Dirk H. Rischke, and Dirk Röder — Institut für Theoretische Physik der Johann-Wolfgang-Goethe-Universität Frankfurt am Main, Robert-Mayer-Str. 8–10, D-60054
Chiral symmetry restoration at nonzero temperature is studied in the framework of the O(4) linear sigma model and the U(Nf)r × U(Nf)ℓ linear sigma model with Nf=2, 3 and 4 quark flavors. We investigate the temperature dependence of the masses of the scalar and pseudoscalar mesons, and the non-strange, strange, and charm condensates within the Hartree approximation as derived from the Cornwall-Jackiw-Tomboulis formalism. We find that the masses of the non-strange and strange mesons at nonzero temperature depend sensitively on the particular symmetry of the model and the number of light quark flavors Nf. On the other hand, due to the large charm quark mass, neither do charmed mesons significantly affect the properties of the other mesons, nor do their masses change appreciably in the temperature range around the chiral symmetry restoration temperature. In the chiral limit, the transition temperatures for chiral symmetry restoration are surprisingly close to the ones found in lattice QCD studies.